The present invention relates to a noise and mechanical vibration reducing apparatus generally used as a pre-muffler in an exhaust system of an internal combustion engine.
In an exhaust system of an automobile, there is provided, at an exhaust pipe, a flexible tube. The flexible tube serves to prevent vibrations caused by the power unit from being transmitted through the exhaust pipe and producing noises by vibrating heat shields installed at the undersides of the exhaust pipe and other exhaust system members.
In such a flexible tube, exhaust gases having a high temperature and a high pressure flow near the corrugated inner surface of the flexible tube and form many vortexes which produce noises such as whistling noise. This result is undesirable.